By GERALD ESKENAZI

Published: January 16, 1989

CINCINNATI—
''IT'S amazing,'' said the hard-driving coach of the Bengals' receivers, Bruce Coslet, ''what a player will do for $5.''

He gives his receivers extra money if they turn the tables and do the hitting. And it has helped the Bengals advance to Super Bowl XXIII, where the winner picks up an additional $36,000 per player in addition to previous playoff winnings.

Considering that receivers are the thin-legged, frail speedsters of football, Coslet's incentive system is a remarkable psychological success story. Those $5 bills couldn't quite be called performance bonuses, which, as everyone knows, are illegal in the N.F.L. if they are not in a contract. The money goes into a pot and buys goodies like a stereo or compact disk player for the locker room.

The Bengals possess one of the most physical group of receivers to go into Super Bowl action.

''Here's what I tell them: they don't play if they don't block,'' said Coslet, who is also the club's offensive coordinator. ''I'm an old tight end.''

He not only shells out money. He collects it if a receiver fails to run the right route or misses his block.

The Bengals' belligerence was symbolized by Tim McGee in the American Conference championship game against the Buffalo Bills. Cris Collinsworth, a backup wide receiver, told McGee that Derrick Burroughs, the Buffalo cornerback, was favoring one leg. McGee went after the bad one with cut-blocking.

It got so bad that the frustrated Burroughs finally smashed McGee with a forearm, and was ejected at a critical part of the game with Cincinnati ahead by only 4 points. Later, McGee disclosed that Bengal receivers received $10 every time they ''decleated'' - knocked off balance - an opposing defensive back. Payoff Doubled in Playoffs

Actually, during the regular season Coslet pays only $5 for the maneuver. In the playoffs, he doubles it. Coslet doesn't really like to talk about the money.

''What about the $10?'' he said with mock exasperation. ''Where did you hear about it? What are you talking about?''

But he explains that getting physical has become a necessity at every position in football these days.

''The players in the secondary now are so big,'' he said. ''Ronnie Lott of the 49ers, who they're going to face, is built like a linebacker. If you don't block him, you're hurting. If you do, you make 6 or 7 yards.''

Think about the Bengals' receivers and the fan immediately conjures up Eddie Brown streaking away from everyone. And why not? His average of 24 yards a catch was by far the best in the N.F.L.

But Brown and McGee must take care of business at the line first. It is crucial to the best offense in football.

Although Boomer Esiason averaged more than 9 yards a completion, far more than any other quarterback, the Bengals actually ran 171 more times than they passed this season. Keeping Defense Off Field

It happened as the result of an off-season decision to keep the suspect defense off the field.

Brown can score so quickly that the defense in past years was getting tired when it had to come back so quickly after his big plays.

So the Bengals decided to try to run. That ate up the clock. The run worked so well, with the rookie Ickey Woods especially, they decided to keep it going.

Now the Bengals' offense had everything its own way. For the defense moved closer to the line, and that allowed Brown to get behind the secondary. McGee, meanwhile, averaged more than 19 yards a catch in his third season. He replaced the three-time Pro Bowler, Collinsworth, who has had several injuries and is just now working his way back into the offense.

''Every time McGee gets into the game he's been a star,'' said Coslet. ''We probably should have gotten him into the game sooner.''

Not surprisingly, Rodney Holman, the tight end, is Coslet's pet on the team. Holman snared only 39 passes, but his blocking is ferocious, his patterns exquisite. He is going to the Pro Bowl.

There is a new wrinkle the Bengals' receivers used this year. On most third-down plays, the Bengals go into the no-huddle quick-snap attack. That forces the defenders to stay with the players they already have; the defense is unable to bring in speedier backs to match up with Brown or McGee.

It has enabled the Bengals to produce the conference's best third-down conversion rate: 44.2 percent. When they go to the line and see the confusion in the defense, Brown knows he has just one route: straight ahead. Esiason unloads the ball. If it's complete, it's a touchdown. If it's not, and the defense is caught offside, it's a free play.